1. Field of the Invention
This invention relates to the servicing of wells through use of coil tubing and more particularly to apparatus for and methods of rotating coil tubing in a well for performing downhole operations therein.
2. Description of the Prior Art
It has been common practice for many years to run a continuous reeled pipe (known extensively in the industry as "coil tubing") into a well to perform operations utilizing the circulation of treating fluids such as water, oil, acid, corrosion inhibitors, cleanout fluids, hot oil, and the like fluids. Coil tubing being continuous, rather than jointed, is run into and out of a well with continuous movement of the tubing through use of a coil tubing injector. This is much quicker than running jointed pipe whose threaded connections consume much time in making and breaking, that is, in assembling and disassembling, or putting them together and taking them apart. Coil tubing injectors are well known in the oil and gas industry.
Coil tubing is frequently used to circulate cleanout fluids through a well for the purpose of eliminating sand bridges or other obstructions therein. Often such sand bridges or other obstructions are very difficult and quite occasionally impossible to remove because of the inability to rotate the coil tubing to drill out such obstructions. Turbo-type drills have been used but have been found to develop insufficient torque for many jobs.
Thus, it is desirable to perform drilling operations in wells through use of coil tubing which can be run into and removed from a well quickly and which can be rotated to perform various and desirable drilling operations such as the removal of obstructions, while also performing the usual operations which require only the circulation of fluids.
Known prior art relating to the present invention includes: U.S. Pat. Nos. 3,191,450; 3,216,731; 3,559,905; 3,865,408; 3,191,981; 3,285,485; 3,690,136; 4,085,796; 3,215,203; 3,313,346; 3,754,474; 4,251,176.
U.S. Pat. No. 3,285,485 which issued to Damon T. Slator on Nov. 15, 1966 discloses a device for handling tubing and the like. This device is capable of injecting reeled tubing into a well through suitable seal means, such as a blowout preventer or stripper, and is currently commonly known as a coil tubing injector.
U.S. Pat. No. 3,313,346 issued Apr. 11, 1967 to Robert V. Cross and discloses methods and apparatus for working in a well using coil tubing.
U.S. Pat. No. 3,690,136 which issued on Sept. 12, 1972 to Damon T. Slator et al discloses apparatus for use with a coil tubing injector to both guide and straighten the coil tubing. The apparatus guides the coil tubing between the reel and the injector with minimal permanent deformation and then straightens the coil tubing when permanent deformation occurs.
U.S. Pat. No. 3,559,905 which issued to Alexander Palynchuk on Feb. 2, 1971 discloses an improved coil tubing injector having a chain drive mechanism which includes not only the usual endless track or drive chain with gripper pads thereon for gripping the coil tubing, but also has an endless roller chain within the track to reduce the friction between the track and the pressure beam, thus providing a good grip on the coil tubing while requiring less horesepower to drive the tracks. This patent also discloses methods and apparatus for running coil tubing into and out of a well without deforming it permanently. Of course, this has no bearing upon the present invention, but the injector with the roller chain within the track is similar to the injector of the present invention which is an improvement thereover.
U.S. Pat. No. 3,754,474 which issued to Alexander Palynchuk on Aug. 28, 1973 discloses an improved gripper pad for use on a track or drive chain of a coil tubing injector.
U.S. Pat. No. 3,215,203 issued to Phillip S. Sizer on Nov. 2, 1965. This patent illustrates and describes apparatus for snubbing jointed pipe into a well against well pressure. A guide tube is provided to prevent buckling of the pipe under heavy column loads. The snubbing apparatus includes both stationary and traveling hydraulically operated slips or grippers of a type usable with the present invention.
U.S. Pat. No. 4,085,796 which issued to Malcolm N. Council on Apr. 25, 1978 illustrates and describes snubbing apparatus similar to that disclosed in U.S. Pat. No. 3,215,203 supra. This patent, in addition, discloses a spline arrangement for maintaining axial alignment of its pistons with its hydraulic cylinders.
U.S. Pat. No. 3,216,731 which issued to William D. Dollison on Nov. 9, 1965 illustrates and describes apparatus including a plurality of strippers, back pressure regulators, and relief valves arranged to step down high well pressure by providing a pressure drop across each stripper in series so that pipe can be snubbed into a well having a surface pressure far greater than that considered safe with the usual stripper arrangement.
U.S. Pat. No. 4,251,176 issued to Phillip S. Sizer and Malcolm N. Council on Feb. 17, 1981 and illustrates and describes apparatus for snubbing pipe into a well. This equipment is shown to use stationary slips or grippers of the general type shown in U.S. Pat. No. 3,215,203, supra, and which could be used in the apparatus of the present invention.
U.S. Pat. No. 3,191,450 which issued to J. H. Wilson on June 29, 1965 illustrates and describes a fluid driven pipe rotating device such as could be used with the apparatus of the present invention.
U.S. Pat. No. 3,191,981 which issued June 29, 1965 to D. W. Osmun and U.S. Pat. No. 3,865,408 which issued Feb. 11, 1975 to Carter R. Young illustrate and describe packoff-type overshots of a type which could be used to connect jointed pipe to coil tubing for well servicing as taught in the present invention.
None of the prior art of which applicants are aware shows, teaches, or suggests apparatus and/or methods which would make it possible to run a length of coil tubing into a well using a coil tubing injector and then rotate the same while it is in the well. Neither does any of the known prior art suggest adding jointed pipe to the upper end of the coil tubing to extend its penetration into the well and to rotate the string of tubing, let alone while moving it up and/or down in the well.